Field of the Invention
The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of preventing image quality degradation due to a kick-back phenomenon.
Discussion of the Related Art
An image display device that implements various types of information on a screen is a core technology in the era of information and communications, and has been developed into a thinner, lighter, mobile, and high-performance device. In this regard, an organic light emitting device that displays an image by controlling the amount of emitted light of an organic light emitting layer, etc. has drawn attention as a flat panel display that can overcome disadvantages of a heavy and large cathode-ray tube (CRT).
The organic light emitting device displays an image by arranging a plurality of pixels in a matrix form. Here, each pixel includes a light emitting element and a pixel driving circuit which independently drives the light emitting element and includes at least a switching thin film transistor (TFT), a storage capacitor, and a driving TFT.
A related art organic light emitting device has a problem of a luminance variation occurring due to deterioration of the light emitting element, a change of channel mobility, and/or a threshold voltage variation of the driving TFT included in each pixel even when the same data voltage is applied to each pixel. To solve this problem, the organic light emitting device uses an external compensation method in which a driving characteristic of each pixel is sensed in real time and data is compensated for in real time using information about the sensed characteristic.
In the external compensation method, the driving characteristic of each pixel is sensed in a blanking period between frame periods in which an image is implemented. In this instance, switching from each frame period to a blanking period incurs a kick-back phenomenon in which a gate voltage and a sensing voltage fluctuate due to parasitic capacitance between a data line and each of a scan line and a sensing line. The kick-back phenomenon varies according to a level of a data voltage supplied to each pixel during each frame period. Values of the threshold voltage and the mobility of the driving TFT sensed through the sensing line have errors due to a kick-back voltage that varies according to the level of the data voltage. Due to an error in the sensing voltage, a compensation value of the data voltage has an error. As a result, image quality is degraded.